3D printed plastic burner experiments (photo heavy)

[Frosty]

I should keep my mouth shut, I haven't cast aluminum since high school but those look like our castings till we ran out of time one class and had to pour before the al was hot enough. Turned out we got much better results if the aluminum was barely molten, actually looked kind of chunky when we poured. We suddenly got better results all round and were able to cast surprisingly thin sections. Danny "G" started casting "porcelain for the patterned" dinner plates and bowls. 

We were green sand casting so perhaps the moisture in the sand was effecting the castings if the aluminum stayed hotter longer.

Just wondering, it's been what 50+ years and . . . ?

Frosty The Lucky.

[D.Rotblatt]

12 hours ago, Frosty said:

better results if the aluminum was barely molten,

Very good observation.  As I recall, pouring too hot causes absorption of gas I believe.  A quick google found mention that this is hydrogen absorption and will cause pinholes. Usually these things don't apply much to the home caster, just to industrial castings - our quantities and time at heat are generally small.  But who knows.  YMMV; I never did much aluminum, mostly bronze.  

Dan R

[Frosty]

The difference in the look when we broke them out was: hot = gray, barely molten = shiny silver. As teenagers we figured hotter was better no matter what the instructor said. However results were what counted and we wanted good castings so examined every one when we broke them out. 

Goodness knows if the sand was too wet the castings came out looking like grinding wheels and one idiot kid, the class joker, barely gave time for the casting to solidify to break it out then take it to the sink to cool it under water. Ruined every casting he attempted. His next series of antics got him banned from the hot area.

We only cast aluminum as a class, the bronze pours were on weekends and advanced "occupational" extra credit activities. I only got in on one with limited success. 

Only 5 or so class members who were serious enough ran the melter, determined when to pour and handled the melt. We poured all the heavy metal shop castings in occupational heavy metal class. Occupational classes started an hour before regular school started and ran 2 hours. You don't leave a green sand mold standing very long in Southern California. I grew up in Sylmar, NE San Fernando Valley. Dry green sand molds do NOT work. Anyway, we developed a technique to assure perfect pour temperature. We'd eyeball as close to right as possible then add a piece of un-molten Al to the crucible and as soon as it started to cottage cheese, pour. 

A contest started between us, we'd put a thumbprint in flat place in the sand, the most readable thumbprint in the casting won. 

One of the guys was using fake hair to imprint hair in his figurines and getting great results. I was initialing castings with a scribe on the bottoms. 

Barely molten was the charm. 

Oh, the joker got himself 86d from metal shop for a couple few pranks. When he couldn't get a decent aluminum ash tray to cast he started punching other guy's molds or picking them up and dropping them. His most egregious mold gag got him banned permanently. He turned one over and scooped sand out of the bottom and laid it back down. Pouring molten aluminum on concrete is NOT recommended procedure, when the concrete exploded it blew the flask to the smoke hood, about 8' and sprayed aluminum for about 25' around. That one got him booted, idiot bragged about it outside the class. It's not like we could watch him constantly, everybody was just too busy.

Eventually he managed to get himself banned for life from ANY Cal, school system shop class. Jamming the guard and feeding a board into the table saw backwards took a number of his fingers off and cut a trench to his elbow. The board speared the wall just above head height across the room. That was his last ever woodshop class. Pouring printer's sulfur in various heater, cooler units around school got him banned from Print shop and stealing various solvents to sniff got him 86d from any crafts shop. I THINK the table saw, paint the shop red incident was his last ever shop class, The 6' hickory spear just endangered too many people.

Sorry for the sidetrack, thinking about and remembering shop class is bringing a lot of memories back.

Frosty The Lucky.

 

[Another FrankenBurner]

The controller ran for the first time today.  It is still on the breadboard but it reads the thermocouple, it cycles the heat relay, and it reads the schedules off of an SD card.

[jlpservicesinc]

Well Done..

[D.Rotblatt]

On 4/1/2019 at 10:01 PM, Another FrankenBurner said:

The controller ran for the first time today.

I want to make one of those for my gas forge!  I'm impressed you built one on a breadboard, any electronics past household or old car circuits is magic to me.  I'll just have to buy a PID.  Well done!

[Frosty]

A light bulb is magic!

Frosty The Lucky.

[Another FrankenBurner]

Thanks guys.  Technology is great, when it works.

As to purchasing a controller, if you search Amazon for a "ramp soak temperature controller," there are several for under $100.  Look for one with PID control and SSR output.  If you just want PID temperature control minus the ramp soak, you can get one for around $30.  On Ebay, I see them as low as $12.  

I had wondered about controlling the fuel output in a forge.  You could on/off the fuel but if the burner could handle lower pressures, a Maxitrol Modulator valve could be used with the proper controller to really dial the temperature in.  As far as I know, this would require an exotic thermocouple type to measure temperatures above 2200°F.

 

I previously mentioned that I purchased some generic tweco 14T-30 mig tips which run a 1/2 inch burner rich compared to the standard Miller 030 tip.  For a minute I thought I had missed the big picture with these burners.  Then I put the Miller 030 tip in and the burner runs beautifully again.  I measured the tips to see why.  The Miller 030 tip is at 0.037 and the generic tweco is at 0.039.  Two thousandths and a poor running burner.  If you are having a problem with a burner but you suspect the mig tip size is close, try another brand.  Now I want to measure several tips to see if same brand tips vary in size per batch.  If the variances are great enough, I may eventually abandon mig tips for capillary tubing or needle stock.

An update on the 450 in³ forge, it likes 4 psi to heat for forge work, a nice high orange.  Also, the idle setting to maintain temperature, on these burners is very low and the forge goes quiet.  It is a bit on the large side but it is great to work with.  

[jlpservicesinc]

They make MIG tips with different internal sizes..   One size for steel wires and one size for alum wires..   the larger size is for the alum wires as they will expand more when heated.. 

Also there is a difference in what the tips are made from..  Some are straight copper and some are more like a copper alloy. 

I use a Binzel mig gun and for a given torch  401D push pull,  I have 24 choices for tips both in size and in length split between type of wire

[Another FrankenBurner]

More experiments are needed with the refractory nozzles.  I very much like them.  Here's one reason why:

These are even the fancier 316 stainless.  The wall thickness is now very thin for most of it's length.

[Mikey98118]

I have been expecting this. The time for refractory nozzles is NOW!

[Latticino]

On 4/8/2019 at 12:47 AM, Another FrankenBurner said:

I had wondered about controlling the fuel output in a forge.  You could on/off the fuel but if the burner could handle lower pressures, a Maxitrol Modulator valve could be used with the proper controller to really dial the temperature in

One trick I've used for this is to have essentially two parallel gas trains, one set for the lowest firing rate my burner would tolerate and the other set for close to maximum output with both sides open.  Then you just hook your PID controller N/C output up to a soleniod valve on the larger side to cycle as required to maintain setpoint.  May not get down to very low temperatures (say HC steel tempering temperatures), but that is all about the turndown ratio of your burner.  The advantage is that you always have a flame going for safety rather than cycling the entire burner on/off and risking superheating the flare or mixing chamber and getting preignition.  Pretty easy to pipe and wire as well.

[Another FrankenBurner]

I have worked with burner systems which employ a similar high/low or on/bypass system.  I overlooked the idea for forge application.  Thank you for pointing it out.  It is a simpler method than the modulating valve and all the things they require.  

 

[Another FrankenBurner]

The kiln now has a ramp/soak controller:

We are excited about it.  I have been studying investment techniques and burnout schedules.  We have a lot of experiments to play with and now they are much easier as the kiln runs itself.

I have been measuring all my different mig tips.  Brand to brand they vary up to 4 thousandths.  In the 1/2 inch burners, 2 thousandths is the difference between blue and green flames.  

My small refrigerant jug forge now has a 1/2 inch burner.  It has a nozzle cast in the wall of the forge.  It runs a hotter temperature, at the same fuel pressure, with a smaller burner with a smaller jet.  The dragons breath is now gone.  The idle setting is very low.  I am happy with the results.  It is a top mounted burner but the inducer head stays comfortable to touch when running even though the short mix tube gets pretty hot.  When I shut the unit down and close the choke, the inducer head gets warm enough that it is unpleasant to touch but not so hot that I worry about it.  

I am a big fan of the bottom mounted burners in the other forge.  The mix tubes stay much cooler.  We leave the chokes open at shut down and the burners chimney cold air in which keeps the inducers temperatures down.  I also wonder if thermal buoyancy helps induce more air when the burners are running.  

[Mikey98118]

7 hours ago, Another FrankenBurner said:

I have been measuring all my different mig tips.  Brand to brand they vary up to 4 thousandths.  In the 1/2 inch burners, 2 thousandths is the difference between blue and green flames.

And now you know why I first started messing with capillary tube five years back

The smaller the burner the more tolerances matter.

[Another FrankenBurner]

I have ordered small brass EDM tubes to play with, on that front.  I want more control for the experiments.  

[Mikey98118]

The smaller the gas jet the smaller, and shorter, the gas tube needed to feed it

[Another FrankenBurner]

Just for Mikey, the quarter inch.  Here it is in my dirty fingers:

The nozzle isn't right yet, we were excited to see it run.  This nozzle is a piece of fire brick which was drilled/filed to get a crude shape.  We will cast a better nozzle soon.  

This guy had a 1 inch length of 0.015 EDM tube for a jet.  It was very lean so an 1/8 inch was removed and the jet drilled to 0.018.  It runs 3 to 20 psi without problems.  More experiments with jet length/size are planned after the nozzle is cast. 

Here is the flame with a house key for size:

The flame is smaller then my propane torch flame.  Now we want to make an impractically small forge to put it in.

 

 

[HojPoj]

No such thing as an impractically small forge, just ambitions that are too big to fit in it!

[Frosty]

SWEET! I'm dieing to hear your definition of impractically small. Just for grins a couple decades ago I turned a freebe sewing machine into a power hammer. The stroke was shorter than I'd like but a 1/4 oz. top die worked sheet copper on pitch surprisingly well. 

How large a forge would you need to make dental picks? Don't forget about all the preparators working on fossils, they need high quality forged tools too! 

Frosty The Lucky.

[Mikey98118]

Excellent! You  are getting longer flames from your 1/4" burner than I could coax from mine. How are your flame retention nozzles coming along; not overheating?

That should make a lovely hand torch flame BTW . You should do a little hard brazing with that burner. just to see how practical it is now.

[Another FrankenBurner]

I was hoping I was going to get crap for slipping that impractically in there.    You guys are great.  I had nails, rivets, and punch tips.  Now I have dentistry and paleontology, thanks Frosty.  I had a one brick forge at 2 inch x 4 inch long at one point.  I used it a bit until the K23 fire brick fell apart.  

When I posted, I had a 1 inch x 3 inch long forge in my head.  I imagine this burner would be grossly too large for that.  It'd be cool though, a good match for the tiny power hammer.  

I was thinking about it and if we take the 3/4" burner 350 in³ rule and divide by seven (mostly because the math is so nice), that burner might be great in a 3 inch x 7 inch long forge.  I plan on building it to find out.  Seems like a handy size.  

I imagine it would be a good burner for the two brick forges that the YouTube knifemakers all seem to like.  I'm going to build mine with the blanket, kasto, top coat route though.

5 hours ago, Mikey98118 said:

You  are getting longer flames from your 1/4" burner than I could coax from mine.

Do you see this as a good thing?  I thought flame length was mostly due to mix tube length, nozzle design, and FAM velocity?  I did find it interesting that it punches through the center of the brick nozzle instead of expanding to the full final size.  I suspect the final outlet diameter is too large and/or the taper is too aggressive.  

5 hours ago, Mikey98118 said:

How are your flame retention nozzles coming along; not overheating?

Some of the designs get very hot, depending on where the flame rides within them.   I like the refractory nozzles because they can accept this.  I have one nozzle, in a forge, which runs partly incandescent without problems.  

Another reason I like refractory nozzles is because I can cast them in whatever shape/size I like.  I have been playing with steps, tapers, and dimensions trying to learn.  

[Mikey98118]

6 minutes ago, Another FrankenBurner said:

I was thinking about it and if we take the 3/4" burner 350 in³ rule and divide by seven (mostly because the math is so nice), that burner might be great in a 3 inch x 7 inch long forge.  I plan on building it to find out.  Seems like a handy size.  

It will be another first. Shall be call it the Tomato-can forge? I think that burner would also run a two-brick forge better than the propane torches that lazy guys keep trying to get by with.

 

[Frosty]

23 hours ago, Mikey98118 said:

call it the Tomato-can forge?

You mean V8 can forge? Picture a blacksmith wreathed in a cloud of yellowish brown smoke slapping his head. The caption reads, "Gosh I coulda had a V8!" What, no dialogue bubble? Nope, it's obscured by the smoke. 

Frosty The Lucky.

[Mikey98118]

Frankenburner is going to need to prefigure cubic inch formulas--especially with smaller burner sizes-- for his design. I was content to let them stand with my hotter Mikey burners, but his flame temperatures are going to need a whole new ballpark!!!

how much? I'm thinking a third hotter!